Implement the reviewed UI icon system and durable review workflow (#853)

Thanks @Nathan-Dane.

docs/robustness.md

@@ -76,11 +76,14 @@ fails, or leaves a sliver face (narrower than 1/200 of the part), it is tried th
 other way too: one way can push a face into a curved face it only touched (a cut
 whose end lies tangent to a round side) and leave a sliver of it, where the other
 way parts them (#897, #827).
-Exact planar and piecewise fallbacks report zero displacement. The existing
-volume and spatial acceptance checks still apply to all results.
-
-The command that adds a feature carries the same `warning` in its reply, so a
-script or an agent sees such a retry without asking the timeline.
+Exact planar and piecewise fallbacks report zero displacement. When a conical
+cutter meets a body with earlier conical faces (pointed bores copied in a pattern),
+two finer, unshifted passes are tried first, at 1e-5 and 1e-6 of their size (never
+below 1e-6 mm). A coarse first cut can leave tiny junctions that later copies cannot
+intersect, so refining only the failing copy is too late. Every candidate must pass
+the volume, membership and spatial checks; a rejected candidate continues to the
+next tolerance, then the ordinary routes. The existing acceptance checks still
+apply to all results.
 
 A join or a cut that needed any retry is then held to what it can do at all
 (`crates/kernel/src/boolean_guard.rs`, #616): the result is closed, a join

docs/ui-icon-design-proposal.md

@@ -0,0 +1,8 @@
+# UI icon design — superseded proposal
+
+The format and style decisions are implemented. SVG masters, theme role mapping,
+isometric geometry and the owner's reviewed set are authoritative.
+
+Use [the binding style guide](../assets/icons/ui/STYLE_GUIDE.md) and
+[the maintained review workflow](../assets/icons/ui/README.md). The earlier
+undecided proposal must not be used to create a competing style or drawing pipeline.

docs/ui-icon-inventory.md

@@ -0,0 +1,22 @@
+# UI icon maintenance
+
+The authoritative authoring specification is
+[assets/icons/ui/STYLE_GUIDE.md](../assets/icons/ui/STYLE_GUIDE.md), with mandatory
+agent instructions beside it. Start at
+[the UI icon README](../assets/icons/ui/README.md) for the included review app,
+canonical resource paths, new-icon scaffold, exports and checks.
+
+Launch the repository-owned review tool with:
+
+```sh
+python3 -B assets/icons/ui/design/tools/icon_status.py --serve
+```
+
+Open http://127.0.0.1:8770/. Every discovered icon without a current acceptance is
+Open. SVGs, aliases and source references are scanned automatically; unused masters
+are included. Counts and CSV reports are derived at runtime, not maintained here.
+`--csv` writes `target/icon-inventory.csv`.
+
+The design and cleanup plan is [ui-icon-maintenance-plan.md](ui-icon-maintenance-plan.md).
+The old proposal is superseded. SVG masters, palette, aliases, the original Rust
+viewport glyphs and owner review records remain the application resources.

docs/ui-icon-maintenance-plan.md

@@ -0,0 +1,82 @@
+# Durable icon maintenance — implementation plan
+
+The goal is for a new contributor or agent, without any chat history, to produce
+icons that match the finished set and to find every icon that still needs review.
+The SVG masters and valid acceptance records must survive this work unchanged.
+
+## 1. Establish ownership and clean the resource tree
+
+- Keep production assets, font licences, platform exports, editable native source
+  documents and the original SVG masters. Never remove an asset used by packaging.
+- Retire superseded numbered authoring batches: they contain duplicate functions,
+  earlier revisions and implicit overrides. The SVGs are the editable authority.
+  Keep a reusable geometry library, explicit bases and a new-icon scaffold instead.
+- Remove the generated inventory CSV from the source collection; generate reports
+  under ignored `target/`. Remove the empty proposal-era stand-in list.
+- Remove the unused historical macOS raster/SVG exports while preserving their
+  editable VectorCraft document. Keep a local recovery copy under `target/`.
+- Update attribution alongside every resource addition, retirement and move.
+
+## 2. Give future authors an unmissable specification
+
+- Link the rules from root AGENTS.md, assets/AGENTS.md and icons/ui/AGENTS.md.
+- Specify the categories, exact palette and weights, isometric projection and
+  face shading, canonical cube/slab bases, action arrows, points, holes, badges,
+  overlap order, detail limits and optical padding.
+- Name finished SVG references for each category and explain what to copy from
+  their visual language. Commercial artwork remains forbidden.
+- Provide a safe starter command that refuses to overwrite an existing icon,
+  and a validation command that checks attribution, structure and coverage.
+- Record a short first-pass acceptance rubric and the complete review workflow.
+
+## 3. Preserve a small, repository-owned review application
+
+- Keep the existing Python entry point and loopback URL, requiring only Python 3.11+.
+- Split the page, CSS and JavaScript into readable versioned source files.
+- Discover SVG masters, aliases, command references, nested UI callers and known
+  wrapper/table arguments on every launch and explicit rescan. Show unused masters.
+- Every discovered, non-final icon is Open, including icons with notes. Missing
+  artwork is visible and cannot be accepted. Report unassigned commands separately.
+- Final means the current artwork matches its saved hash. Changed artwork returns
+  to Open and can be accepted again deliberately; never silently refresh its hash.
+- A normal opening starts at Open / Everything with an empty search. Retain theme
+  and size preferences; preserve temporary filters only for a live artwork reload.
+- Keep autosave, light/dark, small-size variants, notes and portable JSON export.
+  Export queues neutral artwork feedback locally; it does not invoke a model.
+- Preserve notes edited since an export, stale-page merge behavior and accepted art.
+
+## 4. Verify the basic implementation
+
+- Test discovery of newly added and unused masters, aliases, missing artwork,
+  changed acceptance hashes, nested UI callers, stale saves and exact export notes.
+- Check the web UI in both themes and at small sizes. Check the style-reference
+  page and scaffold against the finished geometry.
+- Run focused checks in the background; report actual results. Full repository CI
+  is still required before a local commit. Existing engine robustness failures do
+  not authorize changing unrelated geometry or accepting failed quality gates.
+- Keep this iteration local; do not push or change the existing draft PR #853.
+
+## Scope of this first implementation
+
+No icon redesign, palette change, packaging change, new approval state database,
+cloud service, model-specific automation or replacement of Rust viewport graphics.
+Style quality still needs visual review; lint cannot decide whether a new symbol
+communicates its operation well.
+
+## Basic version implemented
+
+- The media collection retains the production SVGs and platform assets. The
+  superseded bulk generators, generated inventory, empty stand-in list and unused
+  historical exports have been retired; the historical editable native master remains.
+- Mandatory instructions are linked from root, assets and UI-specific AGENTS.md.
+  The style guide, curated references and reusable bases are included in the repo.
+- The review interface is split into versioned HTML/CSS/JavaScript, with discovery
+  on opening/rescan, valid-hash acceptance, visible shared masters, atomic state
+  saves, exact local exports and protection against stale acceptance and note loss.
+- `cargo xtask icons` and the CI repository-check job enforce the icon checks and
+  regression tests. All existing SVG bytes and initial acceptance hashes were preserved.
+
+Remaining limits: source discovery recognises the documented literal call patterns,
+not every possible Rust expression. Add a fixture when introducing a new icon
+wrapper convention. Visual quality, semantic clarity and acceptance remain human
+review decisions; the tool does not automatically redraw or finalise artwork.